The present invention relates to disposable diapers for absorption and contaimnent of bodily discharges. The present application is based on, and claims priority from, Japanese Application Serial Number 2003-009351, filed Jan. 17, 2003, the disclosure of which is hereby incorporated by reference herein in its entirety.
There are well known disposable diapers comprising a liquid-pervious topsheet facing the diaper wearer's skin, a liquid-impervious backsheet facing away from the wearer's skin and a liquid-absorbent core interposed between these sheets and configured to define, in a longitudinal direction, a front waist region, a rear waist region and a crotch region extending between these waist regions. This diaper is curved in the longitudinal direction with the topsheet inside, so urine discharged onto the crotch region may smoothly spread from the urine discharged spot in a transverse direction but not in the longitudinal direction. While urine discharged on the diaper put on the wearer is, in principle, absorbed by the core through the topsheet, such absorption is not completed at once but a certain time is taken until a total quantity of discharged urine is absorbed by the core. In order that the core can absorb the total quantity of discharged urine as quickly as possible, a generally entire area of the core is preferably utilized by facilitating discharged urine to spread in the transverse direction as well as in the longitudinal direction.
To meet such requirement, the disposable diaper including a plurality of splits facilitating discharged urine to spread in the transverse direction and at the same time in the longitudinal direction is disclosed, for example, in Japanese Patent Application Publication No. 1997-51913A. These slits are arranged so as to be spaced apart one from another not only in the transverse direction but also in the longitudinal direction and penetrate the core in its thickness direction. Along these splits, the top- and backsheets are put flat and joined together so that the topsheet forms grooves along these splits. With the diaper disclosed in the above-cited Publication, discharged urine is guided into these grooves to spread in the longitudinal direction and at the same time permeates through the core through its area defined between each pair of the grooves which are adjacent in the longitudinal direction to spread in the transverse direction.
In the case of the diaper disclosed in the above-cited Publication, immediately after it has been discharged onto the topsheet, urine spreads on the topsheet and simultaneously flows into the respective grooves. Depending on the particular spot onto which urine has been discharged, there is a possibility that urine might not immediately flow into the grooves and consequently retard urine to spread in the longitudinal direction. If urine is retarded to spread in the longitudinal direction, most of urine will spread in the transverse direction of the diaper and not only make it impossible to utilize the entire area of the core but also cause sideway leakage of urine from the crotch region.